Suture anchor and method for fixating a suture relative to hard tissue

ABSTRACT

A suture anchor includes a material having thermoplastic properties and is fixated in a hard tissue opening by liquefying at least part of this material and letting it penetrate into walls of the hard tissue opening. During the named fixation and preferably towards the end of it, the suture being held in a distal suture conduit is locked relative to the hard tissue by being clamped between the suture anchor and the wall of the hard tissue opening or by being clamped or braked through collapse of the suture conduit.

FIELD OF THE INVENTION

The invention is in the field of medical technology and concerns asuture anchor and a method for fixating a suture relative to hardtissue, in particular with the aim of attaching soft tissue to the hardtissue with the aid of the suture, wherein the hard tissue is inparticular bone tissue of a human or animal patient.

BACKGROUND OF THE INVENTION

The publications U.S. Pat. No. 7,008,226, WO 2009/109057 and WO2009/055952 (all to Woodwelding) disclose devices and methods forattaching a suture to hard tissue with the aid of a suture anchor,wherein the suture anchor comprises a material having thermoplasticproperties and is anchored in a hard tissue opening with the aid ofpreferably vibratory energy used for in situ liquefaction of thematerial having thermoplastic properties. The liquefied materialpenetrates into pores or other suitable structures of the hard tissue ofthe wall of the hard tissue opening, where on re-solidification itconstitutes a positive fit connection between the hard tissue and thesuture anchor. The anchor comprises the material having thermoplasticproperties on a circumferential surface or in the form of athermoplastic sleeve and it is liquefied when the anchor is forced intothe hard tissue opening and simultaneously vibrated or when the anchoror part thereof is positioned in the hard tissue opening and thethermoplastic sleeve is held between a vibrating tool and a counterelement. The suture is threaded through the proximal or distal end ofthe suture anchor.

Further suture anchors and methods for fixating sutures to hard tissueare disclosed in the publications U.S. Pat. No. 7,678,134, U.S. Pat. No.7,695,495, US-2006/161159, 2009/192546, US-2009/187216 (all to Arthrex),U.S. Pat. No. 5,733,307 (Dinsdale), or U.S. Pat. No. 6,508,830(Steiner), wherein the disclosed anchors comprise an interference screwto be screwed into a bone opening provided for the purpose, or a plugpreferably made of bone material to be press-fitted into a bone openingprovided for the purpose, wherein the suture is either held by the screwor plug or by an additional element being retained in the opening withthe aid of the screw or plug.

Methods of anchoring an item in an opening provided in hard tissue, e.g.in bone tissue of a human or animal patient with the aid of a materialhaving thermoplastic properties which is liquefied in situ and made topenetrate the hard tissue of the wall of the opening are furthermoredisclosed in the publications U.S. Pat. No. 7,335,205, US-2006/0105295,US-2008/109080, US-2009/131947, WO-2009/109057, and WO-2009/132472.Therein preferred energy used for the liquefaction is mechanicalvibration energy. The disclosure of all the named publications andapplications is enclosed herein by reference.

SUMMARY OF THE INVENTION

It is the object of the invention to create a further suture anchor anda further method for fixating a suture relative to hard tissue, whereinthe suture anchor is fixated in a hard tissue opening with the aid of amaterial having thermoplastic properties which is liquefied in situ topenetrate the hard tissue of the wall of the hard tissue opening.Therein the suture anchor and the method are to be suitable forattaching soft tissue to the hard tissue with the aid of the suture, andthe hard tissue is to be in particular bone tissue of a human or animalpatient. The suture is preferably fixated relative to the suture anchoror the hard tissue respectively in a non-slideable manner (suturelocking), wherein suture tension may be adjustable during at least aninitial section of the fixation process. However, the suture anchoraccording to the invention may also serve for establishing a slideablesuture fixation. The method including suture locking is in particularsuitable for per se known knotless procedures for suturing soft tissueto hard tissue. Furthermore, the suture anchor and method according tothe invention are to be capable of safeguarding the suture againstundesired influence caused by the in-situ liquefaction (i.e., in thecase of liquefaction through mechanical vibration, against undesiredinfluences of friction and heat), and to therefore allow use inconnection with friction and/or heat sensitive sutures. Furthermore, adistal end of the anchor may be equipped for enhancing retainment of thesuture anchor in the hard tissue opening, in particular in hard tissuewith only little mechanical stability.

The suture anchor according to the invention comprises a material havingthermoplastic properties at least on surface portions to be in contactwith the hard tissue in the hard tissue opening or preferably itconsists fully of such a material, wherein at least part of the materialhaving thermoplastic properties is liquefied in situ and penetrates thehard tissue of the walls of the opening. The distal suture end comprisesa suture conduit for holding the suture, e.g. a distal suture groove, asuture channel or an eyelet, of more than one such conduit or acombination of different ones of such conduits. The suture anchor isdesigned, in particular, for locking the suture relative to the anchorin a last phase of the process of fixating the anchor in the hardtissue, wherein the locking of the suture is achieved either by clampingthe suture between the anchor and the hard tissue in the hard tissueopening or by braking or clamping it through collapse of the sutureconduit or suture conduits. This means that the locking of the suturedoes principally not depend on the fixation process in which the sutureanchor is fixated or anchored in the hard tissue opening, which allowssafeguarding the suture against possibly damaging influences of theliquefaction process (heat, vibration) and/or allows adjustment of thesuture tension during or possibly even after the anchoring process.

Furthermore, the suture anchor may comprise structures preferably in adistal end portion which structures are capable of being spread orradially expanded by suture tension and/or abutment of the distal anchorend against the bottom of a blind opening, which spreading or expandingenhances retainment in or beyond the hard tissue opening. The namedspreading is e.g. effected during the liquefaction process by thetensioned suture being forced against or into the anchor materialproximal to the suture conduit when this anchor material is mechanicallyweakened by absorption of heat, which may result in distal anchorsections being forced apart, such spreading the distal anchor portion.In a further embodiment a portion of the anchor is designed to becollapsible under a compressive load and can therewith be radiallyexpanded e.g. under the influence of the suture tension.

For the fixation process, for which mechanical vibration energy (inparticular ultrasonic vibrational energy) is preferably used, the sutureanchor according to the invention is forced into the hard tissue openingand simultaneously the liquefaction energy is transmitted into thematerial to be liquefied. For this purpose, a tool suitable fortransmitting a pushing force and the vibrational energy to the anchor isused, a distal end of the tool being preferably attached to the proximalface of the suture anchor and a proximal end of the tool being coupledto a vibration source. This fixation process does not necessitate anyrotation of the suture anchor, i.e. the suture anchor is not screwedinto the hard tissue opening and therefore preferably does not comprisea screw thread.

The vibration source is in particular a source of ultrasonic vibration(e.g. piezoelectric vibration generator possibly comprising a booster towhich the tool is coupled) and the tool is suitable for transmission ofthe vibration from its proximal end to its distal face, preferably suchthat the distal face vibrates with a maximal longitudinal amplitude. Forthe in situ liquefaction, the distal face of the tool is applied to theproximal face of the suture anchor. It is possible also to activate thetool to vibrate in a radial or in a rotational direction.

Alternatively, the energy source may be a laser, preferably emittinglaser light in the visible or infrared frequency range and the tool isequipped for transmitting this light to its distal end, preferably viaglass fiber. For the in situ liquefaction, the laser light is absorbednear the distal tool face or in the suture anchor, wherein in the lattercase the material having thermoplastic properties comprised by thesuture anchor may contain particles or substances effecting suchabsorption. Furthermore, the energy source may be a source of electricenergy which e.g. heats an electric resistor in a distal tool portion orwhich causes eddy currents and therewith thermal energy near the distaltool face or in the suture anchor.

Suitable in situ liquefaction of a material having thermoplasticproperties with the aid of vibration energy combined with an acceptablethermal loading of the tissue and suitable mechanical properties of thepositive fit connection to be produced is achievable by using materialswith thermoplastic properties having an initial modulus of elasticity ofat least 0.5 GPa and a melting temperature of up to about 350° C. incombination with vibration frequencies preferably in the range ofbetween 2 and 200 kHz (preferably 15 to 40 kHz, or even more preferablybetween 20 and 30 kHz). The modulus of elasticity of at least 0.5 GPa isin particular necessary if the material having thermoplastic propertiesis to transmit the vibration without loss of mechanical stiffness.

Materials having thermoplastic properties suitable for the suture anchoraccording to the invention are thermoplastic polymers, e.g.: resorbableor degradable polymers such as polymers based on lactic and/or glycolicacid (PLA, PLLA, PGA, PLGA etc.) or polyhydroxy alkanoates (PHA),polycaprolactone (PCL), polysaccharides, polydioxanes (PD)polyanhydrides, polypeptides or corresponding copolymers or compositematerials containing the named polymers as a component; ornon-resorbable or non-degradable polymers such as polyolefines (e.g.polyethylene), polyacrylates, polymetacrylates, polycarbonates,polyamides, polyester, polyurethanes, polysulfones, polyarylketones,polyimides, polyphenylsulfides or liquid crystal polymers LCPs,polyacetales, halogenated polymers, in particular halogenatedpolyolefines, polyphenylensulfides, polysulfones, polyethers orequivalent copolymers or composite materials containing the namedpolymers as a component.

Specific embodiments of degradable materials are Polylactides like LR706PLDLLA 70/30 (e.g. filled with up to 30% biphasic calciumphosphate),R208 PLDLA 50/50, L210S, and PLLA 100% L, all of Böhringer. A list ofsuitable degradable polymer materials can also be found in: ErichWintermantel und Suk-Woo Haa, “Medizinaltechnik mit biokompatiblenMaterialien und Verfahren”, 3. Auflage, Springer, Berlin 2002 (in thefollowing referred to as “Wintermantel”), page 200; for information onPGA and PLA see pages 202 ff., on PCL see page 207, on PHB/PHVcopolymers page 206; on polydioxanone PDS page 209. Discussion of afurther bioresorbable material can for example be found in CA Bailey etal., J Hand Surg [Br] 2006 April; 31(2):208-12.

Specific embodiments of non-degradable materials are Polyetherketone(PEEK Optima, Grades 450 and 150, Invibio Ltd), Polyetherimide,Polyamide 12, Polyamide 11, Polyamide 6, Polyamide 66, Polycarbonate,Polymethylmethacrylate, Polyoxymethylene, or polycarbonate-urethane(e.g. Bionate by DSM, in particular types 65D and 75D). An overviewtable of polymers and applications is listed in Wintermantel, page 150;specific examples can be found in Wintermantel page 161 ff. (PE,Hostalen Gur 812, Höchst AG), pages 164 ff. (PET), 169ff. (PA, namely PA6 and PA 66), 171 ff. (PTFE), 173 ff. (PMMA), 180 (PUR, see table), 186ff. (PEEK), 189 ff. (PSU), 191 ff (POM—Polyacetal, tradenames Delrin,Tenac, has also been used in endoprostheses by Protec).

The material having thermoplastic properties may further contain foreignphases or compounds serving further functions. In particular, thethermoplastic material may be strengthened by admixed fibers or whiskers(e.g. of calcium phosphate ceramics or glasses) and such represent acomposite material. The material having thermoplastic properties mayfurther contain components which expand or dissolve (create pores) insitu (e.g. polyesters, polysaccharides, hydrogels, sodium phosphates),compounds which render the implant opaque and therewith visible forX-ray, or compounds to be released in situ and having a therapeuticeffect, e.g. promotion of healing and regeneration (e.g. growth factors,antibiotics, inflammation inhibitors or buffers such as sodium phosphateor calcium carbonate against adverse effects of acidic decomposition).If the thermoplastic material is resorbable, release of such compoundsis delayed. If the device is to be anchored not with the aid ofvibration energy but with the aid of electromagnetic radiation, theliquefiable material having thermoplastic properties may locally containcompounds (particlulate or molecular) which are capable of absorbingsuch radiation of a specific frequency range (in particular of thevisible or infrared frequency range), e.g. calcium phosphates, calciumcarbonates, sodium phosphates, titanium oxide, mica, saturated fattyacids, polysaccharides, glucose or mixtures thereof.

Fillers used may include degradable, osseostimulative fillers to be usedin degradable polymers, including: β-Tricalciumphosphate (TCP),Hydroxyapatite (HA, <90% crystallinity); or mixtures of TCP, HA, DHCP,Bioglasses (see Wintermantel). Osseo-integration stimulating fillersthat are only partially or hardly degradable, for non degradablepolymers include: Bioglasses, Hydroxyapatite (>90% cristallinity),HAPEX®, see SM Rea et al., J Mater Sci Mater Med. 2004 September;15(9):997-1005; for hydroxyapatite see also L. Fang et al., Biomaterials2006 July; 27(20):3701-7, M. Huang et al., J Mater Sci Mater Med 2003July; 14(7):655-60, and W. Bonfield and E. Tanner, Materials World 1997January; 5 no. 1:18-20. Embodiments of bioactive fillers and theirdiscussion can, for example, be found in X. Huang and X. Miao, JBiomater App. 2007 April; 21(4):351-74), JA Juhasz et al. Biomaterials,2004 March; 25(6):949-55. Particulate filler types include: coarse type:5-20 μm (contents, preferentially 10-25% by volume), sub-micron(nanofillers as from precipitation, preferentially plate like aspectratio >10, 10-50 nm, contents 0.5 to 5% by volume). Experiments showthat liquefaction with the aid of ultrasonic vibration energy allowsfilling the thermoplastic polymer to a relatively high degree withoutimpairing the capability of the liquefied material to penetratestructures as e.g. the trabecular structure of viable cancellous bone.

The suture anchor according to the invention may, in addition to thematerial having thermoplastic properties, also comprise portions (e.g. acore) of material having no thermoplastic properties or thermoplasticproperties which are not suitable for in situ liquefaction under theconditions of the fixating process (non-liquefiable materials). Suchportions may consist of any suitable material (e.g. polymer, metal,ceramic, glass) which may be bio-resorbable or not bio-resorbable. Suchnon-bioresorbable or non-biodegradable portions may comprise surfacesequipped for furthering osseointegration (e.g. per se known surfacestructures or coatings) where in contact with the bone tissue, inparticular if the material having thermoplastic properties isbio-resorbable or bio-degradable and therefore the anchoring functionneeds to be gradually taken over by osseointegration. Suitablenon-liquefiable materials, which are bio-resorbable, are e.g. polylacticacid (PLA) filled with Hydroxyapatite or calciumphosphates, inparticular PLLA filled with 60% tricalciumphosphate.

The vibration tool can be designed very slim and approximately 200 mmlong or even longer. Therefore, the suture anchor and method accordingto the invention are in particular suitable for minimally invasivesurgery but are also applicable in open surgery. The vibration toolpreferably has a length corresponding to half of the vibrationwavelength in the tool material or of this half wavelength multipliedwith an integer factor, the theoretical half wavelength e.g. for a toolmade of titanium grade 5 and for a vibration frequency of 20 kHz being126.5 mm, for a vibration frequency of 25 kHz 101.2 mm.

The device and method according to the invention as above described arein particular applicable for substantially all surgical procedures in ahuman or animal patient, in which surgical procedure a suture needs tobe attached to hard tissue and locked relative to the latter, some ofthe embodiments being in particular advantageous in hard tissue of onlylittle mechanical strength. In the same manner, the suture anchor andthe method according to the invention are applicable for attaching asuture to a replacement material having features comparable to thefeatures of hard tissue, or to part hard tissue part replacementmaterial or to a further implant (e.g. endoprosthesis) wherein theimplant needs to be suitably equipped, e.g. with undercut openings.

Examples of such applications are the fixation of a soft tissue (inparticular ligament, tendon or cartilaginous tissue) to bone tissue in aso called knot-less single row procedure, e.g. fixation of a rotatorcuff to underlying bone tissue (or a corresponding endoprosthesis),Achilles tendon repair, reattachment of the acetabular labrum to theacetabulum or the glenoid labrum to the scapula or, as lateral anchorsin a so called double row procedure (see FIG. 1). In the latter case itis advantageous to use the same fixation process for fixation of theanchors (without the suture locking) of the medial row also. Preferreddevices and methods for fixating such medial anchors are e.g. disclosedin a co-pending application claiming the same priority. However, thesuture anchor and the method according to the invention may also be usedfor slideable attachment of a suture to hard tissue (e.g. for the medialanchors in a double row procedure).

Further exemplary applications of the anchor and method according to theinvention are e.g. regarding the human shoulder joint: the Bankartrepair or the repair of SLAP-lesions (superior labrum anterior toposterior), regarding the human hand: the UCL-repair (ulnar collateralligament) as treatment for “skier's thumb” (acute condition) or“gamekeeper's thumb” (chronic condition), the SL-reconstruction(scapholunate ligament), the TFCC-repair (triangularfibrocartilagecomplex), or the capsular reattachment of themetacarpophalangeal joint, regarding the human elbow: ulnar collateralligament reconstruction (Tommy John surgery), regarding the human foot:the Bromstrom repair, the peroneal retinacular repair or halux valgusreconstruction, and regarding the human knee: iliotibial band tenodesis.Generally speaking, the suture anchor and method according to theinvention are particularly advantageously applicable in repair surgeryregarding ligaments in the human hand and wrist (ligaments ofinterphalangeal, metaphalangeal and carpometaphalangeal joints andcarpal ligaments) and in the human foot and ankle joint.

BRIEF DESCRIPTION OF THE DRAWINGS

The suture anchor and the method according to the invention aredescribed in further detail in connection with the appended Figs.,wherein:

FIG. 1 illustrates four successive phases of the per se known double rowprocedure using the example of a rotator cuff repair, in which procedurethe anchor according to the invention preferably constitutes the anchorsof the lateral row but possibly also the anchors of the medial row;

FIG. 2 shows an exemplary embodiment of the suture anchor according tothe invention, the suture anchor being suitable for locking the suturebetween the hard tissue and the suture anchor;

FIG. 3 shows a further exemplary embodiment of the suture anchoraccording to the invention, the suture anchor being suitable for lockingthe suture by collapsing the suture conduit;

FIGS. 4 to 6 show further and alternative features applicable for thesuture anchors shown in FIGS. 2 and 3;

FIG. 7 shows in detail the distal end of an exemplary vibration toolsuitable for fixation of the suture anchor according to FIG. 6;

FIGS. 8 to 12 show further exemplary embodiments of distal ends forsuture anchors according to the invention which are e.g. suitable forfixation in hard tissue of only little mechanical stability.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates the per se known double row procedure for suturing asoft tissue to a hard tissue, using the example of reattaching a tornrotator cuff tendon 10 to humeral bone tissue 11 (or a correspondingendoprosthesis) in four successive phases (a), (b), (c) and (d). Phase(a) is before the repair operation and shows the location 12 in whichreattachment is necessary. In phase (b) two medial anchors 13 areanchored in the bone tissue, in locations to eventually be locatedunderneath the tendon 10, each one of the medial anchors 13 attaching atleast one suture 4 to the bone tissue in a slideable manner. In phase(c) the end sections of each suture attached to one of the medialanchors is passed through the torn tendon 10 and by tensioning thesutures away from the tendon end (not shown), the latter is pulled overthe medial anchors 13. In phase (d) two lateral anchors 14 are anchoredin the bone tissue just beyond the edge of the tear, the row of lateralanchors 14 running about parallel to the row of medial anchors 13, theend sections of the sutures 4 being tensioned and locked with the aid ofthe lateral anchors 14 in a cross-wise manner, such that the two sutureend sections held by one medial anchor 13 are locked by two differentlateral anchors 14 such forming crossed suture bridges 15 between therow of medial anchors 13 and the row of lateral anchors 14. Therein eachrow of anchors may comprise two or more than two anchors and each medialanchor 13 is used for attaching at least one suture 4 (two suture endportions) and each lateral anchor 14 is used for locking at least twosuture end portions originating from two different medial anchors 13.

As already mentioned further above, the suture anchor and the methodaccording to the invention are in particular advantageously applicablein the lateral row, but correspondingly adapted are also applicable inthe medial row.

FIGS. 2 and 3 illustrate exemplary embodiments of the suture anchoraccording to the invention. These suture anchors 2 comprise a materialhaving thermoplastic properties (liquefiable material) or they arepreferably made of such a material and they are anchored in a hardtissue opening by in situ liquefaction of at least part of the materialhaving thermoplastic properties and by making the liquefied materialflow into the hard tissue to constitute, when re-solidified, a positivefit connection between the anchor and the hard tissue. The anchoringmethod on which the anchors, according to the invention, are based isdisclosed e.g. in the publication U.S. Pat. No. 7,335,205, thedisclosure of which is enclosed herein in its entirety. According tothis method a proximal face of the anchor is contacted with a tool whichtransmits energy into the anchor, in particular a vibration tool whichtransmits vibrational energy. Simultaneously the anchor is pushed into ahard tissue opening having a cross section which is slightly smallerthan the cross section of the anchor portion to be fixated in theopening, such that anchor portions comprising the material havingthermoplastic properties get into intimate contact with the hard tissue,which in the case of the use of vibrational energy serves also ascounter element necessary for transforming the vibrational energy intofriction heat for the in situ liquefaction.

Furthermore, the suture anchors according to FIGS. 2 and 3 comprise atleast one distal suture conduit (e.g. distal groove, channel, or eyelet)in which the suture is held when the suture anchor is positionedrelative to the hard tissue opening and fixated therein, and structuresfor locking the suture relative to the fixated anchor or the hard tissuerespectively either by clamping it between the suture anchor and thewall of the hard tissue opening (FIG. 2) or by collapsing the sutureconduit and such braking or clamping the suture threaded therethrough(FIG. 3).

The suture anchor 2 as shown in FIG. 2 comprises a pin portion 20 andadvantageously a head portion 21 and is shown attached to a tool 1, bye.g. a press fit connection between a tool protrusion reaching into arecess in the head portion 21 (not shown). At least the pin portion 20comprises at least at parts of its lateral surfaces the material havingthermoplastic properties and advantageously, as illustrated, energydirectors e.g. in the form of axial edges extending over part of the pinlength and being offset relative to each other in adjoining such partlengths (the pin portion has e.g. as illustrated the form of a stack ofmisaligned polygon-shaped discs). The head portion 21 may also comprisethe material having thermoplastic properties and may also be anchored inthe hard tissue, in which case the hard tissue opening provided for theanchor 2 will need to have a stepped form including a narrower innerportion for accommodation of the pin portion 20 and a larger outerportion for accommodation of the head portion 21. Alternatively, thedistal face of the head portion my be anchored in the hard tissuesurface around the mouth of the opening provided for the pin portion.

The pin portion 20 comprises a suture groove 22 running across thedistal pin face and, in an axial direction, along two opposite pinsides, wherein the suture groove 22 comprises at least one portion whichis undercut, the undercut groove portion 23 being situated e.g. asillustrated, on the distal pin face (suture conduit). Preferably, theoverall cross section of the suture groove 22 is adapted to the sutureor sutures to be locked with the aid of the anchor such that thesuture(s) running along the groove does not protrude from the groove,i.e. does not get into contact with the hard tissue when the pin portion20 is pushed into the hard tissue opening provided therefore while beingvibrated. This measure serves for preventing damage of a friction and/orheat sensitive suture on fixation of the anchor, in particular whenusing vibrational energy for such fixation. When using a suture of nosuch sensitivity the suture may as well protrude from the suture grooveand therewith rub on the wall of the hard tissue opening, wherein suchfriction may help to at least primary stabilization of the suturerelative to the suture anchor.

The undercut portion 23 of the suture groove 22 is dimensioned such thatthe suture to be locked with the aid of the anchor can be entered intothe undercut groove by resiliently deforming the groove entrance andthat the suture is safely kept in the undercut groove portion 23 when noforce acting perpendicular to the groove length pulls the suture out ofthe undercut groove portion 23.

The suture groove 22 continues on both sides of the head portion 21, butat the transition between pin and head portion comprises an interruption24, i.e. it has a depth on a proximal end of the pin portion 20 whichdecreases with decreasing distance form the head portion 21, azero-depth portion (or portion with relevantly reduced depth) at thetransition between the pin and the head portion, and a depth on a distalside of the head portion 21 which increases with increasing distancefrom the pin portion 20. This measure serves for clamping the suturebetween the hard tissue and the implanted anchor for locking it.

The head portion 21 has a larger cross section than the distal end ofthe tool 1 such that, when the anchor 2 is attached to this distal toolend, the proximal face of the head protrudes beyond the distal face ofthe tool at least on those two sides on which the suture groove reachesthis proximal head face. As illustrated, the distal tool end may have acircular cross section and the head portion an oval cross section havinga smaller diameter which is the same as the tool diameter and a largerdiameter spanning between the mouths of the suture grooves. This measureserves for preventing a friction and/or heat sensitive suture fromcontact with the tool 1, in particular with the edge of the distal toolface, which is particularly advantageous when the tool is a vibrationtool and the suture is of a friction and/or heat sensitive type.

For fixating a suture relative to hard tissue using the anchor 2 asillustrated in FIG. 2, a hard tissue opening is provided, a crosssection of at least an inner portion of the hard tissue opening beingadapted to the pin portion 20 of the anchor 2 such that a distal end ofthe pin portion 20 having the smallest cross section fits easily intothe opening but the rest of the pin portion 20 can be introduced intothe opening using a pressing force only. The pin portion 20 of theanchor which is attached to the tool being coupled to an energy source(preferably vibration source) is positioned into the mouth of theopening, the suture to be fixated by the anchor running along the suturegroove 22 and extending out of the hard tissue opening on both sides ofthe anchor. The pressing force is then applied to the suture anchor viathe tool, the desired suture tension is established and the energysource is activated (tool and anchor vibrated). Where in intimatecontact with the hard tissue wall of the opening, the material havingthermoplastic properties is liquefied and penetrates into the hardtissue. At the same time the anchor is pushed further into the openingand is finally anchored when the head portion 21 abuts the hard tissuesurface or a step in the hard tissue opening. Only at the very end ofthe described anchoring process, the suture is clamped between the hardtissue in the region of the mouth of the hard tissue opening or the stepin the opening and the suture anchor at the transition from the pinportion 20 to the head portion 21, which transition location only thenreaches the hard tissue. This means that the suture, if correspondinglyadapted to the suture groove, remains slideable (possibly against somefriction between suture and tissue inside the hard tissue opening)relative to the anchor during an initial part of the fixation step andtherefore the suture tension can still be adapted or maintained up towhen the anchor is very close to its final fixated position.

Further embodiments of the suture anchor as illustrated in FIG. 2 maye.g. not comprise a head portion, comprise energy directors of adifferent type or no energy directors at all and/or may comprise a corenot being made of the material having thermoplastic properties butcomprising a sleeve of or being coated with the latter at least on thepin portion and possibly excepting the suture groove 22 and the distalpin end.

When used for locking sutures which are neither friction nor heatsensitive, and without the possibility of the late tension adjustment,the suture groove may be present at the distal face of the pin section20 only (zero depth suture groove portion extending along the entireanchor length), where it may be undercut or may have a cross sectiondimensioned for holding the suture by friction. The same effect can beachieved with a suture anchor as shown in FIG. 2 and a suture having across section greater than the cross section of the suture groove 22(possibly not having a zero depth portion at all), wherein the sutureprotrudes from the groove. For achieving a slideable attachment of thesuture to the hard tissue using the suture anchor according to FIG. 2 ora similar suture anchor, a suture of a diameter smaller than the reduceddepth of the zero-depth groove portion is used, or the anchor isintroduced into the hard tissue opening only such that the zero-depthgroove portion protrudes from the opening or the opening is providedwith a mouth of a larger cross section to accommodate the zero-depthgroove portion without clamping the suture.

Furthermore, the head portion 21 may comprise a protrusion suitable forattachment of the anchor 2 to the tool 1 which has a correspondingrecess in its distal face. Furthermore, the suture anchor according toFIG. 2, in particular the embodiment comprising a core of e.g. a metalmay comprise a tapering or sharpened distal end for being able to beforced at least into cancellous bone without the necessity of providingan opening therein beforehand or of providing such opening only throughthe cortical bone. The forcing of the suture anchor 2 into the bonetissue is preferably effected using the same tool as used for theanchoring step but without transmitting energy for the liquefaction tothe suture anchor.

The anchor as illustrated in FIG. 3 differs form the anchor asillustrated in FIG. 2 mainly regarding the means provided for the suturelocking, which in this case are located at the distal anchor end beingequipped for holding the suture. This distal end has a smaller crosssection than the rest of the anchor and comprises two eyelets 25 (sutureconduit) and it consists of a material which is plastically deformableor becomes plastically deformable under the influence of energytransmitted into the anchor for its fixation in the hard tissue suchthat a compressive load, caused through the suture tension and/or byabutment against a bottom wall of a blind hard tissue opening is able tocollapse it (collapsible suture conduit). The suture 4 to be fixated andlocked with the aid of the anchor 2 is threaded through the two eyelets75 and runs along the anchor length e.g. in a suture groove as describedfurther above in connection with FIG. 2, but not shown in FIG. 3.

The anchor 2 as illustrated in FIG. 3 is fixated in a hard tissueopening 5 much as discussed above in connection with FIG. 2, wherein thedistal pin end comprising the two eyelets 25 is made to collapse by thesuture being tensioned against the anchor and/or by pushing it againstthe hard tissue on the bottom of the opening 5 provided for the anchor2, wherein by such collapse the suture 4 is locked due to its bendingradius between the two eyelets 25 being reduced and therewith suturebraking increased in such a manner that the suture cannot slidetherethrough any more and/or due to the decreasing cross section of theeyelets 25 which causes the suture 4 to be clamped. In such a case thezero-depth portion of the suture groove as described above is not neededfor securely locking the suture, which means that in this latter case,there may be no contact at all between the suture 4 and the hard tissuewithin the opening 5.

FIG. 3 shows, in a very schematic manner, the anchor 2 in threesuccessive phases (a), (b) and (c) during the fixation and lockingprocess. In phase (a) the anchor 2 being attached to the distal end ofthe tool 1 is positioned in the mouth of the hard tissue opening 5, thesuture 4 running through the two eyelets 25 and out of the opening 5 atone side of the anchor 2 to be held by any suitable means. In phase (b)the tool 1 is activated by the not shown energy source and the anchor 2is pushed further into the opening 5, while the suture 4 is kepttensioned or the suture tension is increased, possibly against frictionbetween the suture and the tissue in the hard tissue opening. In phase(c), fixation of the anchor 2 and locking of the suture 4 are complete,the distal end of the anchor 2 abutting the bottom of the hard tissueopening 5 and comprising the two eyelets 25 being collapsed to brakeand/or clamp the suture. The moment during the anchoring process inwhich the suture conduit is collapsed is determined by the suturetension which for this purpose needs to be sufficiently high and/or bythe depth of the hard tissue opening 5. Up to the moment of the collapseof the eyelets 25, the suture 4 may remain slideable relative to theanchor, the same as discussed above in connection with FIG. 2.

For providing a slideable suture attachment using the suture anchoraccording to FIG. 3, the suture tension is to be kept sufficiently lowand/or the hard tissue opening needs to be sufficiently deep.

The features listed above for further embodiments of the suture anchoraccording to FIG. 2 are, correspondingly adapted, also applicable forthe suture anchor according to FIG. 3. Furthermore, features of thesuture anchors according to FIGS. 2 and 3 can also be combined whichresults in further embodiments such as e.g. the suture anchor of FIG. 2comprising a distal channel or eyelet for holding the suture, orcomprising any distal suture conduit being collapsible, or the sutureanchor of FIG. 3 comprising a collapsible distal groove which may beundercut, or comprising axial suture grooves with or without a proximalzero-depth portion.

FIGS. 4 to 6 illustrate further exemplary embodiments of the sutureanchor and method according to the invention, wherein some of theseembodiments are mentioned already above as possible variations of thesuture anchors according to FIGS. 2 and 3.

FIG. 4 shows a suture anchor 2 which is quite similar to the anchor asshown in FIG. 2 but other than the latter comprises a pin portion 20only (no head portion) and instead of one suture groove foraccommodation of one suture comprises two (or possibly more than two)suture grooves 22 and 22′ for accommodation of two (or possibly morethan two) sutures, wherein the two suture grooves extend cross-wiseacross the distal anchor face (suture conduits), where they are possiblyundercut, and continue in an axial direction along the circumferentialpin portion surface, preferably as illustrated regularly spaced fromeach other and ending at a distance from the proximal anchor face(zero-depth groove portions 24).

In the same manner as illustrated in FIG. 4, the suture anchor accordingto FIG. 3 may be equipped for anchoring more than one suture bycomprising two or more than two distal suture conduits (eyelets)arranged at an angle to each other and possibly axial suture grovesextending in a proximal direction from the mouths of the conduits.

FIG. 5 shows a suture anchor 2 similar to the suture anchors accordingto FIGS. 2 and 4 but comprising a suture groove 22 with an undercutdistal groove portion 23 (suture conduit) constituting two groovelevels, wherein the groove 23.1 of the inner level comprises a smallercross section and in particular a narrower mouth than the groove 23.2 ofthe outer level, such that a thinner suture will enter the inner groove23.1 and be safely held therein and a thicker suture possibly not beingable to enter the inner groove 23.1 will be safely held in the outergroove 23.2. The suture anchor according to FIG. 5 is e.g. capable ofresiliently holding sutures of a thread size from 0 to 3-0, wherein athicker suture (e.g. size 0) will be held in the outer groove 23.2 and athinner suture (e.g. 3-0) in the inner groove 23.1. This means that theanchor according to FIG. 5 is the same applicable for quite differentthread sizes.

FIG. 6 illustrates a further means for safeguarding the suture to befixated and possibly locked in hard tissue with the aid of the sutureanchor according to the invention against possibly damaging influencescaused by vibration or heat produced in the anchoring process. Thesefurther means are an equivalent to the head portion having a largercross section than the tool used for implanting the anchor as shown inFIG. 2. Other than according to FIG. 2, in the present case, thesafeguarding means are arranged on the tool 1 which is used for fixatingthe suture anchor in the hard tissue opening and which comprises atleast on a distal end portion lateral grooves 26 which are arranged tobe aligned with the proximal ends of the suture groove 22 of the sutureanchor 2. The same as the protruding anchor head portions illustrated inFIG. 2, these lateral grooves 26 of the tool 1 prevent the suture fromcoming into contact with the edge of the distal face of the tool, whichis in particular important for a vibration tool and for a suture whichis friction and/or heat sensitive. If a zero-depth groove portionadjoins the proximal anchor face as illustrated in FIGS. 4 and 5 and thetool comprises a distal face adapted to the proximal anchor face orbeing slightly smaller, such measure does not have any advantage.

FIG. 7 shows a distal face of a tool 1 comprising the lateral grooves 26as discussed above and further comprising a protrusion 27 having anelongate, e.g. rectangular or oval cross section. In cooperating with acorrespondingly shaped depression in the proximal anchor face attachmentof the suture anchor to the distal tool end automatically results inproper alignment of the suture grooves 22 and the lateral grooves 26.Instead of a protrusion of an elongate cross section on the distal toolface and a corresponding depression in the proximal anchor face, twoprotrusions of an e.g. circular cross section and two correspondingbores in the proximal anchor face can be provided. The same is achievedobviously by the protrusion(s) being provided on the proximal anchorface and the depression(s) on the distal tool face.

FIGS. 8 to 11 illustrate distal ends of exemplary embodiments of thesuture anchor according to the invention which embodiments constitutealternatives to distal anchor ends as shown in FIGS. 2 to 6. The sutureanchor embodiments according to FIGS. 8 to 11 comprise in the samemanner as the suture anchor embodiments according to FIGS. 2 to 6 adistal suture conduit (groove, channel or eyelet) extending angledrelative to an anchor axis across a distal anchor face or through adistal anchor end portion. The anchor comprising a material havingthermoplastic properties at least in the region of its circumferentialsurface is fixated in a hard tissue opening by having a cross sectionwhich is slightly larger than the cross section of the hard tissueopening and by being forced into the hard tissue opening andsimultaneously being vibrated preferably by applying to a proximalanchor face a vibration tool being coupled e.g. to an ultrasonicvibration generator. The material having thermoplastic properties isliquefied at the interface between the vibrating suture anchor and thehard tissue of the wall of the opening provided for the suture anchorand penetrates this hard tissue to form on re-solidification a positivefit connection between the suture anchor and the hard tissue.

Using the suture anchors according to FIGS. 8 to 11, the fixation oranchorage established with the aid of the material having thermoplasticproperties and the vibration energy (similar to the fixation oranchorage as discussed in connection with the previous figures), isenhanced by forcing apart distal anchor sections or expanding anchorportions, the forcing apart and the expansion being caused by the suturewhich during the fixation process is tensioned against the pushing forceof the vibration tool and is therewith forced into or against the anchorportion proximal to the suture conduit and/or by the distal suture endbeing pushed against the bottom of a blind hard tissue opening intowhich the anchor is forced. Preferably this effect is further enhancedby providing for this anchor portion a material which is softened andthereby weakened on application of the liquefaction energy and/or bydesigning this anchor portion mechanically weaker than other anchorportions. Such spreading or expansion will enhance the retainment of thesuture anchor constituted by the material having thermoplasticproperties penetrated into the hard tissue of the wall of the opening,which is particularly advantageous if this hard tissue is e.g.cancellous bone tissue of only little mechanical strength positionedunderneath a cortical bone layer. It is possible also that the spreadanchor sections or the expanded anchor portion are situated beyond thehard tissue opening (on a non accessible side of a bone plate orcortical bone layer) and by having a larger cross section than theopening help retaining the anchor in the opening. It is obvious that inthe latter case spreading and expansion can only be achieved through thesuture tension.

FIGS. 8 to 10 show exemplary embodiments of distal ends of sutureanchors 2 comprising distal anchor sections 2.1 and 2.2 on either sideof the distal portion of the suture groove 22 (undercut or not undercut)which distal anchor sections are forced apart and therewith pressedagainst the walls of the hard tissue opening such producing anadditional press fit or positive fit by compressing the tissue of thesewalls during or possibly before the anchoring process. The distal anchorsections 2.1 and 2.2 are forced apart by the suture running through thedistal groove 22 being pulled in a proximal direction (through exteriorsuture tension or through friction between the suture and the wall ofthe opening during advancement of the anchor into the hard tissueopening) and forced into the groove bottom, possibly assisted by acorresponding anchor design and/or a softening effect of the energytransmitted into the anchor for the liquefaction process.

FIGS. 8 to 10 are very schematic axial sections through distal endportions of suture anchors 2 comprising a suture groove 22 extending atan angle (preferably a right angle) to the anchor axis and separatingthe distal anchor portion into two distal sections 2.1 and 2.2. On theleft hand side of the figures, a suture 4 is held in the suture groove22, the suture not being tensioned (pulled in a proximal direction) ornot tensioned enough for being able to deform the distal anchor portion,and on the right hand side of the figures, the suture 4 is tensioned andmoved in a proximal direction therewith forcing apart or spreading thedistal anchor sections 2.1 and 2.2.

FIG. 8 shows in addition a pair of transversal bores 36 orientatedparallel to the distal suture groove 22 and situated underneath thegroove bottom for weakening the corresponding anchor portion andtherewith allowing the suture under tension, and possibly with theanchor material further weakened by the energy transferred into it forthe liquefaction process, to be pulled into the suture material of thegroove bottom and therewith spreading the lateral suture sections apartas shown on the right hand side of FIG. 8.

FIG. 9 shows an undercut distal suture groove 22 and an additionalspreader element 37 located in the suture groove underneath the sutureand having e.g. the form of a wedge. The spreader element 37 whichpreferably consists of a harder material or of a material with a highermelting or softening temperature than the suture anchor 2 is able to cutinto the anchor material when forced against the bottom of the suturegroove 22 by the tensioned suture.

FIG. 10 shows the distal suture groove 22 and the suture 4 runningthrough the latter. The suture groove 22 and the suture 4 extend at anangle (preferably a right angle) to the spreader element 37 for which afurther groove 37.1 is provided. The two grooves 22 and 37.1 separatethe distal anchor portion into four sections wherein the two sections onthe one side of the spreader groove 37.1 are forced apart from the twosections on the other side of the spreader groove by the spreaderelement 37 being forced into the bottom of the spreader groove 37.1 bythe suture being tensioned, and wherein the two sections on the one sideof the suture groove 22 may in addition be forced apart from the twosections on the other side of the suture groove, if the tensioned sutureis also forced into the bottom of the suture groove 22.

FIG. 11 illustrates the additional expansion by collapse of an anchorportion caused by the suture tension and/or by the distal anchor endbeing pushed against the bottom of the hard tissue opening. The anchor 2comprises again a distal suture groove 22 and at least one (e.g. two)transversal bore 36 extending through the anchor 2 in a direction angledrelative to the suture groove 22. The transversal bores 36, which cannotserve as a sort of perforation of the distal anchor portion as discussedin connection with FIGS. 18 and 19, form thin material portions whichlocally initiate absorption of the vibration such weakening thecorresponding anchor portion and enabling collapse of the transversalbores and therewith local expansion of the anchor as shown on the righthand side of FIG. 11.

FIG. 12 illustrates in the same manner as FIGS. 8 to 11, a furthermeasure for enhancing suture anchor retainment in bone tissue of an onlylimited mechanical strength, in particular in a blind opening of such abone tissue. For enhancing softening and liquefaction in the distalanchor face even with very little counteraction by the bottom wall ofthe opening, the distal anchor end portion comprises thin and therewithmechanically weak portions of the material having thermoplasticproperties, which weak portions tend to get softened or liquefied underthe influence of the vibration used for the fixation process with hardlyany friction on a counter element which in the present case is the bonetissue. This measure results in a collapse and therewith slight radialexpansion of the distal anchor end portion and/or in a good penetrationof the bone tissue situated around the distal anchor end portion, whichmay take over a main part of the anchoring function such that forlateral anchorage necessary friction on the lateral wall of the hardtissue opening may be reduced to a minimum.

Good results in corresponding experiments were achieved with distalanchor faces 38 of a concave shape (e.g. hollow cone or frustum as shownin FIG. 12), but can also be achieved with distal anchor faces withother hollow shapes, possibly additionally slotted or with distal anchorsections separated by grooves (e.g. suture groove) as shown in severalprevious Figures. The distal end of the suture anchor according to FIG.12 additionally comprises two (or more than two) transversal bores 36serving as weakening structures as discussed in connection with FIGS. 8,9, and 11 and/or as possibly collapsible suture conduits.

All the measures illustrated in FIGS. 8 to 12 are applicable e.g. inanchors as previously described. However, they are also applicable inanchors having other characteristics. For this reason, the inventionalso concerns an anchor (preferably suture anchor) and a method forfixating the anchor in a hard tissue opening comprising only thefeatures as disclosed in FIGS. 8 to 12 and serving for enhancing anchorretainment in the hard tissue opening. The corresponding anchor ischaracterized by a distal end portion comprising end sections separatedby a groove, by a concave distal face, or by a weakened anchor portionproximally adjoining a distal suture conduit. The corresponding methodis characterized by spreading the end sections, or by collapsing andtherewith expanding the weakened anchor portion, the concave distal faceor the end sections through tensioning of the suture or through abuttingthe anchor against the bottom of a blind hard tissue opening.

In the above described embodiments, according to FIGS. 8 to 11, thesuture being fixated relative to hard tissue may have a specificfunction (spreading or expanding a distal anchor portion) in the methodaccording to which the suture anchor is fixated in the hard tissue. Ifthese embodiments of anchors are to be used in other applications thanas suture anchors or in combination with sutures which are mechanicallytoo weak for the named functions, it is possible to make use of a suturesubstitute, to position and use this suture substitute instead of or inaddition to the suture as described and to finally remove it or clip endportions of it. Such suture substitutes may be any flexible andelongated item such as e.g. a wire, a ribbon or a suture of suitablecharacteristics. The term “suture” as used in the above descriptionencompasses such suture substitutes.

The above described invention concerns in particular suture anchorssuitable for soft tissue attachment to hard tissue. In all the describedembodiments of methods for fixating such suture anchors in hard tissue,the sutures may be further safeguarded against damage by heatdissipating from the material having thermoplastic properties whenliquefied, by being soaked with liquid (water or saline solution)preferably before being threaded through the distal suture conduit orbefore being positioned in the hard tissue opening and necessarilybefore liquefaction of the material having thermoplastic properties.

In all above described methods for attaching soft tissue to hard tissuewith the aid of a suture anchor and a suture, a material havingthermoplastic properties is liquefied to preferably penetrate hardtissue or cavities provided in the hard tissue to constitute whenre-solidified a positive-fit connection between the anchor or partthereof and the hard tissue of the wall of the opening. Such positivefit connections can in all described cases be achieved also in atwo-step procedure, wherein the walls of the hard tissue opening arepre-treated according to a method as described in the publicationsWO-2010/045751 or WO-2009/141252 (Nexilis), wherein a material havingthermoplastic properties is forced in a liquefied state into the hardtissue of the wall of the opening to form together with this tissue asort of composite substantially without coating this wall with thematerial having thermoplastic properties. In a second step the anchoringprocess is then carried out as described in the present description andin the cited publications, wherein the liquefied material is not able topenetrate the composite material of the wall of the opening establishedin the pre-treatment step, but instead is welded to the compositematerial of this wall. For such welding it is a condition that thematerial having thermoplastic properties used in the second or fixationstep is weldable to the material having thermoplastic properties used inthe first or pre-treatment step. Preferably the two materials havingthermoplastic properties comprise the same thermoplastic polymer.

If the named pre-treatment step is carried out in a manner to form thecomposite material comprising the hard tissue and the material havingthermoplastic material right to the mouth of the hard tissue opening,this mouth is strengthened and therewith has an enhanced capacity toresist being cut by the suture fixated in the hard tissue opening by theanchor fixated therein, when this suture is tensioned.

What is claimed is:
 1. A suture anchor in combination with a suture,said suture anchor being adapted to lock the suture relative to a hardtissue, the suture anchor comprising: a pin portion, said pin portiondefining a suture conduit at a distal end of the pin portion and asuture groove portion extending in an axial direction along acircumferential surface of the pin portion, the suture groove portionreceiving an axially running portion of the suture held in the sutureconduit, a circumferential surface of said pin portion comprising amaterial having thermoplastic properties, wherein, for locking thesuture relative to the hard tissue, the suture groove portion comprisesa zero depth portion at a proximal end of the pin portion, wherein thezero depth portion extends distally from the proximal end of the pinportion, and wherein the suture anchor is designed in a single pieceform.
 2. The suture anchor and suture according to claim 1, wherein thesuture anchor further comprises a head portion.
 3. The suture anchor andsuture according claim 1, wherein the suture conduit at the distal endof the pin portion is an undercut groove extending across a distal faceof the pin portion.
 4. The suture anchor and suture according to claim3, wherein, the suture conduit has: an outer mouth, an outer cavityproximally of the outer mouth, the outer cavity having a diametergreater than a width of the outer mouth so that the suture conduit formsan undercut groove, the suture conduit further having, proximally of theouter cavity, an inner mouth, and an inner cavity proximally of theinner mouth, a diameter of the inner cavity being greater than a widthof the inner mouth, wherein the inner mouth is narrower than the outermouth, whereby the inner cavity is capable of accommodating a suture ofsmaller thread size than the outer cavity.
 5. The suture anchor andsuture according claim 1, wherein the suture conduit at the distal endof the pin portion is a suture channel or an eyelet.
 6. The sutureanchor and suture according to claim 1, wherein the suture anchorfurther comprises at least one of a spreader element positioned in thesuture conduit or in a spreader groove arranged to cross the sutureconduit and a weakened and therewith collapsible anchor portionadjoining the suture conduit proximally.
 7. The suture anchor and sutureaccording to claim 6, wherein the weakened portion comprises at leastone transversal bore.
 8. The suture anchor and suture according to claim1, further comprising a concave distal face.
 9. A method for fixating asuture in hard tissue with the aid of a suture anchor, the methodcomprising the steps of: providing the suture and the suture anchor,said suture anchor comprising: a pin portion, said pin portion defininga suture conduit at a distal end of the pin portion and a suture grooveportion extending in an axial direction along a circumferential surfaceof the pin portion, the suture groove portion receiving an axiallyrunning portion of the suture held in the suture conduit, acircumferential surface of said pin portion comprising a material havingthermoplastic properties, wherein, for locking the suture relative tothe hard tissue, the suture groove portion comprises a zero depthportion at a proximal end of the pin portion, wherein the zero depthportion extends distally from the proximal end of the pin portion, andwherein the suture anchor is designed in a single piece form; providinga hard tissue opening having a cross section dimensioned for the pinportion needing forcing for introduction into the hard tissue opening,forcing the pin portion of the suture anchor into the hard tissueopening while transmitting energy into the suture anchor for a timesufficient to liquefy at least part of the material having thermoplasticproperties where in contact with the hard tissue inside the hard tissueopening, and locking the suture by clamping it between the hard tissueand the suture anchor at the zero-depth suture groove portion, andwherein the suture anchor is designed in a single piece form.
 10. Themethod according to claim 9, wherein the energy transmitted into thesuture anchor is mechanical vibration energy and wherein, in the step offorcing and transmitting, a vibration tool is used, the suture anchorbeing attached to a distal face of the vibration tool.
 11. The methodaccording to claim 9, wherein, during the step of forcing andtransmitting, distal end sections of the suture anchor separated by thesuture groove or by a spreader groove are spread away from each other bythe suture being tensioned or by the distal end of the suture anchorbeing pushed against a bottom of the hard tissue opening.
 12. The methodaccording to claim 11, wherein a spreader element is positioned in thesuture conduit or in the spreader groove.
 13. The method according toclaim 9, wherein, during the step of forcing and transmitting, an anchorportion adjoining the suture conduit proximally is radially expandedunder the compressive force of the suture being tensioned or of thedistal end of the suture anchor being pushed against a bottom of thehard tissue opening.
 14. A kit of parts comprising: a suture, a sutureanchor, and a vibration tool, wherein the suture anchor comprises: a pinportion, said pin portion defining a suture conduit at a distal end ofthe pin portion and a suture groove portion extending in an axialdirection along a circumferential surface of the pin portion, the suturegroove portion receiving an axially running portion of the suture heldin the suture conduit, a circumferential surface of said pin portioncomprising a material having thermoplastic properties, wherein, forlocking the suture relative to the hard tissue, the suture grooveportion comprises a zero depth portion at a proximal end of the pinportion, wherein the zero depth portion extends distally from theproximal end of the pin portion, and wherein the suture anchor isdesigned in a single piece form; the vibration tool is suitable forfixating the suture anchor in a hard tissue opening by positioning adistal tool face against a proximal anchor face and transmitting apushing force and mechanical vibration from the vibration tool to thesuture anchor, wherein the proximal anchor face comprises at least onemouth of the suture groove extending in an axial direction along acircumferential surface of the suture anchor, and wherein the distaltool face and the proximal anchor face are adapted to each other suchthat the distal tool face does not cover the at least one mouthcomprised by the proximal anchor face, when the distal tool face ispositioned against the proximal anchor face for the fixation process.15. The kit of parts according to claim 14, wherein the distal tool faceand the proximal anchor face have different shapes such that a portionof the proximal anchor face in which the at least one mouth is situatedprotrudes from the distal tool face when the distal tool face ispositioned against the proximal anchor face for the fixation process.16. The kit of parts according to claim 15, wherein the distal tool faceis circular and the proximal anchor face is oblong, in particular oval.17. The kit of parts according to claim 14, wherein the tool comprisesat least one lateral groove comprising a mouth in the distal tool face,the mouth being adapted and aligned or alignable with the mouth in theproximal anchor face.
 18. The kit of parts according to claim 14,wherein one of the distal tool face and the proximal anchor facecomprises at least one protrusion and the other one of the distal toolface and the proximal anchor face comprises a depression, the at leastone protrusion and the at least one depression cooperating for arrangingthe suture anchor at a distal tool end with the distal tool facepositioned against the proximal anchor face, such that the at least onemouth in the proximal tool face is not covered by the distal tool face.19. A method for fixating a suture and a suture anchor in hard tissuewith the aid of in situ liquefaction of a material having thermoplasticproperties, the method comprising the steps of: providing the suture andthe suture anchor, the suture anchor comprising: a pin portion, said pinportion defining a suture conduit at a distal end of the pin portion anda suture groove portion extending in an axial direction along acircumferential surface of the pin portion, the suture groove portionreceiving an axially running portion of the suture held in the sutureconduit, a circumferential surface of said pin portion comprising amaterial having thermoplastic properties, wherein, for locking thesuture relative to the hard tissue, the suture groove portion comprisesa zero depth portion at a proximal end of the pin portion, wherein thezero depth portion extends distally from the proximal end of the pinportion, and wherein the suture anchor is designed in a single pieceform providing a hard tissue opening, introducing the suture anchor withthe suture extending through the distal suture groove into the hardtissue opening by pushing the suture anchor into the hard tissue openingusing a tool and by simultaneously transmitting energy via the tool tothe suture anchor, thereby liquefying the material having thermoplasticproperties, where in contact with a wall of the hard tissue opening,while keeping the suture tensioned and therewith forcing the sutureagainst a bottom of the distal suture groove, and forcing distal anchorsections away from each other by forcing the suture through the bottomof the distal suture groove into the suture anchor and/or expanding thesuture anchor by compressing it between the tool and the suture.
 20. Themethod according to claim 19, wherein the suture anchor comprises atleast one transversal bore extending parallel to the distal suturegroove beyond the bottom of the distal suture groove, and wherein thesuture enters the at least one bore when forced through the bottom ofthe suture groove.
 21. The method according to claim 19, wherein thesuture anchor comprises at least one transversal bore extending at anangle to the distal suture groove beyond the bottom of the suturegroove, and wherein the transversal bore is collapsed when the sutureanchor is compressed between the suture and the tool.
 22. The methodaccording to claim 20, wherein the at least one transversal bore extendsthrough the material having thermoplastic properties, and wherein theenergy transmitted to the suture anchor is vibrational energy.
 23. Amethod for fixating a suture in hard tissue with the aid of a sutureanchor, the method comprising the steps of: providing the suture anchorcomprising a pin portion, said pin portion defining a suture conduit ata distal end of the pin portion and a suture groove portion extending inan axial direction along a circumferential surface of the pin portion,the suture groove portion receiving an axially running portion of thesuture held in the suture conduit, a circumferential surface of said pinportion comprising a material having thermoplastic properties, wherein,for locking the suture relative to the hard tissue, the suture grooveportion comprises a zero depth portion at a proximal end of the pinportion, wherein the zero depth portion extends distally from theproximal end of the pin portion, and wherein the suture anchor isdesigned in a single piece form; the suture conduit having an outermouth, an outer cavity proximally of the outer mouth, the outer cavityhaving a diameter greater than a width of the outer mouth so that thesuture conduit forms an undercut groove, the suture conduit furtherhaving, proximally of the outer cavity, an inner mouth, and an innercavity proximally of the inner mouth, a diameter of the inner cavitybeing greater than a width of the inner mouth, wherein the inner mouthis narrower than the outer mouth, whereby the inner cavity is capable ofaccommodating a suture of smaller thread size than the outer cavity, andwherein the inner mouth and the outer mouth are each constituted by twoinwardly projecting portions arranged at equal axial positions and lyingdirectly opposed to each other, providing a hard tissue opening having across section dimensioned for the pin portion needing forcing forintroduction into the hard tissue opening, forcing the pin portion ofthe suture anchor into the hard tissue opening while transmitting energyinto the suture anchor for a time sufficient to liquefy at least part ofthe material having thermoplastic properties where in contact with thehard tissue inside the hard tissue opening, and locking the suture byclamping or braking it by collapsing the suture conduit.